The present invention relates to forage harvesters of the type which are pulled by towing vehicles such as tractors and which include a means for chopping cut crop material and for blowing the cut crop material into a forage wagon towed behind the forage harvester.
Forage harvesters of this type generally include a hitch pole for connecting the forage harvester to a tractor and are towed behind the tractor at a position to one side of its center line. The prior art forage harvesters also include a rotatable drive shaft connecting the power take-off shaft of the tractor to an input shaft of a transmission on the forage harvester for driving the various moving parts of the forage harvester such as the cutting cylinder and the blower fan. Since the forage harvester is positioned to one side of the center line of the tractor, the rotatable drive shaft is generally disposed at an angle to the input shaft of the transmission. As a result, universal joints providing a driving connection between the drive shaft and the input shaft are subject to chatter and are subjected to unnecessary wear.
It is desirable that the forage wagon towed by the forage harvester be coupled to the forage harvester at a position generally in alignment with the discharge chute of the forage harvester blower. As a result, in many prior art forage harvesters, the forage wagon is attached to the forage harvester at a position which is laterally spaced, with respect to the direction of motion of the forage harvester when it is being towed, from the point where the hitch pole is attached to the forage harvester. Consequently, the forces applied by the hitch pole upon the forage harvester when it is being towed and the drag on the forage harvester applied by the forage wagon create a moment on the forage harvester tending to cause it to skew with respect to the direction of its movement. The head attachment of the forage harvester is thus misaligned with respect to crop rows, and the efficiency of the forage harvester is substantially affected. The problem of skewing of the forage harvester becomes particularly critical when it is used in muddy conditions wherein the forage wagon places a more substantial drag on the forage harvester.
Forage harvesters which have a blower mounted in a laterally spaced relationship with respect to the chopping cylinder and head attachment of the forage harvester have been found to be advantageous over the prior art forage harvesters because the discharge chute of the blower and the forage wagon can be positioned more directly behind the point of attachment of the hitch pole. This arrangement prevents the weight of the forage wagon from causing skewing of the forage harvester when it is being pulled through a field. However, due to the lateral separation of the blower and the chopping cylinder necessitated by this arrangement, it is necessary to provide a means to convey the cut crop material from the chopping cylinder to the blower. The prior art mechanisms for providing this intermediate conveying means incorporated the use of such devices as screw-type auger systems. These auger systems have not proved completely satisfactory because the cut crop material such as long grasses or wet green crops can cause the augers to be plugged up, and the cut crop material also tends to build up around the circumference of the auger thereby causing a frictional drag on the auger requiring unnecessary amounts of power to drive the auger. Furthermore, the blower fan, which rotates at high speeds, could be used to cause substantial air flow through the auger housing to convey the cut crop material but for the presence of the auger. The use of the augers is thus inefficient because the air flow generated by the blower is not used to its fullest advantage. Finally, due to the structure of the cutting cylinder in the prior art forage harvesters, it has generally been necessary to support the auger behind the cutting cylinder and to force the cut crop material rearwardly toward the auger. With this arrangement, the space below the cutting cylinder tends to become clogged with cut crop material resulting in further inefficient use of the horsepower required to drive the cutting cylinder.